The invention concerns a water-cooled X-ray source for generating both a point focus as well as a line focus comprising                a radiation protection casing,        an X-ray tube element, which is inserted into the radiation protection casing and has a filament and an X-ray anode,        a cooling plate having water channels for cooling the X-ray anode of the X-ray tube element,        a spray jet via which cooling of the X-ray anode takes place, wherein the spray jet has a slit arranged parallel to the filament,        and cooling water channels to the cooling plate,wherein the radiation protection casing, the cooling plate and the cooling water channels are firmly connected to each other.        
Such an X-ray source is known, for example, through the company publication “Diffraction solutions D8 ADVANCE” by Bruker AXS GmbH, Karlsruhe 2006.
X-ray diffraction is a powerful instrumental analysis method, with which a specimen is exposed to a generally monochromatic X-ray beam and a deflection of the X-ray beam, generally brought about by diffraction on the crystalline lattice of the specimen material, is measured.
X-ray radiation is generated in an X-ray tube by way of electrons emerging from a glowing filament which are accelerated onto an X-ray anode in an electrical field. When the electrons strike the anode, they are decelerated and X-ray radiation is released.
An elongated filament can be used both to produce a point focus as well as a line focus. In the former case, the filament is aligned parallel to the effective radiation direction, in the latter case the filament is perpendicular to the effective radiation direction. An X-ray tube designed for both types of focus has at least one exit window for each type of focus. In order to select a focus type for an experiment, an appropriate exit window of the X-ray tube is used.
When the electrons are decelerated on the anode, the anode heats up and is cooled in order to prevent it from burning through. Cooling water is supplied to the rear of the anode using a spray nozzle which is parallel (e.g. the exit slit) to the filament.
In the case of the “D8 ADVANCE” type X-ray device, a cooling plate is arranged on the X-ray tube through which cooling water channels pass. The cooling water channels supply the spray nozzle, which is, in turn, connected to the cooling plate. The cooling plate is supplied with cooling water via cooling water pipelines arranged rigidly on the radiation protection casing. In order to avoid incorrect assembly, a predetermined, fixed alignment of the cooling plate vis-à-vis the radiation protection casing is given by way of an index pin; in the same way, a particular fixed alignment of the cooling plates vis-à-vis the X-ray pipe is also given by an index pin.
In order to change the focus in the “D8 ADVANCE” type X-ray source, the X-ray source, including the cooling water flow, has to be switched off and largely dismantled. Another cooling plate (replacement cooling plate also known as a 90° cooling plate) with cooling water connections/index pins displaced through 90° is mounted on the X-ray tube and the protective casing. Changing the focus is therefore extremely time-consuming and there is the risk of leaking residual cooling water into the sensitive X-ray apparatus.
From the company document “X'pert Materials Research Diffractometer system—new horizons in materials research” by Philips Analytical, Almelo, Netherlands, an X-ray tube has become known in which the cooling water pipelines are integrated into a mountable cooling plate. In this way, the X-ray tube can be turned in a protective casing in order to change the focus. However, this X-ray tube is large and cumbersome due to the cooling water pipelines passing through it; the rear connection elements of the cooling water to the X-ray tube—hoses, for example, also have to be rotated when changing the focus. Integration of the cooling water pipelines also increases the cost of the X-ray tube; the X-ray tube is a special component.
Departing therefrom, the aim of the present invention is to provide an X-ray source with which it is possible to easily change between different types of focus, wherein conventional X-ray tubes can preferably be used in the X-ray source.